This invention relates to an epoxy resin composition useful for sealing electronic parts, to a process for producing the same, and to a resin-sealed semiconductor device.
In recent years, transfer molding has been conducted using an economically advantageous epoxy resin for sealing a semiconductor such as LSI, IC, transistor and the like.
In particular, quite recently, the surface mounting of LSI has been conducted and the case of direct immersion in a solder bath has been increased. In this case, the sealing material is exposed to a high temperature not lower than 200.degree. C., and hence, such a problem occurs that the moisture contained in the sealing material is vaporized and expanded to cause cracks or cause peeling at the interface with a die pad.
At present, the mainstream is a sealing material in which a glycidyl ether of o-cresol novolak is used as an epoxy resin and a phenol novolak is used as a curing agent. Because of the above problem, however, the sealing material is practically used in the moistureproof package form.
Hence, the resin sealing material is strongly required to have soldering resistance. In general, for improving the crack resistance, modification with a rubber such as butadiene-acrylonitrile copolymer rubber, silicone rubber or the like is effected, thereby improving the impact resistance. However, the rubber-modification results in a reduction in strength and modulus of elasticity though the impact resistance can be improved, and hence, the rubber-modification is not a preferable method for the improvement of the soldering resistance aimed at in this invention.
Under such circumstances, the present inventors have made extensive research on an epoxy resin composition excellent in soldering resistance and have consequently found that an epoxy resin composition containing an aromatic polyamide pulp and highly filled with an inorganic filler can solve the above-mentioned problems.